1. Field of the Invention
A tool that connects plates or plate pieces that are overlapping, or plates with connecting points (punching rivets, screw bolt attachments, or the like) through the process of riveting (clinching, or the like).
2. Description of Related Art
According to a known tool (DE 44 35 460, FIG. 3), the sheathing pieces of the matrix, radially outward flexible, are moved against the force of spring plates. At the same time, these spring plates serve the purpose of attaching the matrix pieces to the matrix body. To this end, the matrix pieces are bolted at one end to the matrix body, and at the other end, they are bent and slide into the grooves of the corresponding sheathing pieces. There is also a flexible belt between the spring plates and the matrix pieces for the purpose of giving additional support and guidance to the matrix pieces. One disadvantage is the fact that this spring arrangement is a disturbance factor. Since these heavy-duty tools are exposed to rough conditions, the springs can loosen, which in turn can result in defective connecting points. In addition, it can require expensive reworking measures or the replacement of work pieces, since the automatic manufacturing does not allow for an immediate assessment of the defects. The other disadvantage is the fact that the installation of the tool, the mounting of the spring plates, as well as the setting up of the sheathing pieces is difficult and complex and, consequently, expensive.
There is another known tool of the same kind (EP 0744231 B1) in which, through the work piece material that is displaced between punch and base plate, two sheathing pieces placed opposite to each other are pushed apart against the force of the corresponding spring. The springs have a connecting section which runs transverse to the driving direction and is located in a groove underneath the base plate of the matrix. During the working process, with the aid of the spring-loaded sheathing pieces, the plates that have to be connected are first partly punched and then compressed. In this way, during the process of compression, some of the partly punched plates can move transverse to the direction of the sheathing pieces. Apart from the fact that, as a result of the punching, the plates are not connected tightly, this connection is also less durable than the connection made with the above-mentioned clinching tool. However, the reset springs of the sheathing pieces are also exposed to less pressure so that such a simple multi-cranked leaf spring could be used. It is also very easy to remove the work piece from the tool. But this tool is not able to make a clinching connection without cutting through the plate, not even if adjustments are made. However, this is also not intended since the connections are made with a completely different procedure.
Another known tool (EP 0835701 A 2) provides only two expanding pieces as alternatable sheathing pieces, which are held in place with metal springs. The two springs are connected with casing rings. Even in this case, the springs are only exposed to the pressure of two sheathing pieces placed opposite to each other. Therefore, it is actually not possible to monitor the displaced plates and their movement.
Another known tool (PCT-WO 97/029 12, DE 32 10 208) has a spring ring around the sheathing pieces which opens during the clinching process and the movement of the sheathing pieces. Even in this case, there is the disadvantage that the ring presents a disturbing factor, especially in the form of wear debris and the like, which can result in early wear-out. In addition, during the working process with this tool, the plates are partly clinched.
There is yet another tool (GB 2069394) in which the sheathing pieces of the matrix are connected in one piece with the matrix on the side opposite to the punch. Like a cantilever, they take on the work of the spring. The disadvantage of this tool is especially its high production costs as well as its lack of flexibility.